Piece sets, from Lichess (https://github.com/lichess-org/lila/tree/master/public/piece), which
optimized the SVG files. Only the set published on the admin page shows to visitors.

cburnett  Colin M.L. Burnett           GPLv2 or later, used under GPLv3 (see /engine/COPYING.txt)
merida    Armando Hernandez Marroquin  GPLv2 or later, used under GPLv3 (see /engine/COPYING.txt)
chessnut  Alexis Luengas               Apache License 2.0 (see chessnut/LICENSE.txt)
          https://github.com/LexLuengas/chessnut-pieces
kosal     philatype                    CC BY 4.0, https://github.com/philatype/kosal
fantasy   Maurizio Monge               MIT (see fantasy/LICENSE.txt), https://github.com/maurimo/chess-art
mpchess   Maxime Chupin                GPLv3 (see /engine/COPYING.txt)
          https://github.com/chupinmaxime/mpchess-pieces
rhosgfx   RhosGFX                      CC0 1.0, https://rhosgfx.itch.io/vector-chess-pieces
pixel     therealqtpi                  AGPLv3 or later (see /sounds/AGPL-3.0.txt)
letter    usolando                     AGPLv3 or later (see /sounds/AGPL-3.0.txt)
shapes    flugsio                      CC BY-SA 4.0, https://github.com/flugsio/chess_shapes
chesscom  Chess.com "Neo"              Chess.com's own artwork, not hosted here: loaded from
                                       images.chesscomfiles.com only when published

CC BY 4.0: https://creativecommons.org/licenses/by/4.0/
CC BY-SA 4.0: https://creativecommons.org/licenses/by-sa/4.0/
CC0 1.0: https://creativecommons.org/publicdomain/zero/1.0/